I have configured
PHP and MySQL
500 Internal Server Error
I'm willing to bet that your templates_c directory is not writable by Apache (identified as apache or httpd, and you can check in your httpd.conf file), or it hasn't been configured correctly during Smarty initialization.
You can try temporarily setting your templates_c directory to 777 permissions to test this hypothesis.
If this ends up being the case, then you'll want to assign group ownership of templates_c to apache, and set the folder permissions to 775. (They explain this in their documentation.)